The present invention relates to a method of manufacturing a semiconductor device, using a flexible tube, and specifically to a method of using a flexible tube in a semiconductor manufacturing apparatus and manufacturing a semiconductor device by the semiconductor manufacturing apparatus.
A number of chemical materials are used in the manufacture of a semiconductor device. In particular, the semiconductor device undergoes many manufacturing processes associated with chemical reactions. Since the chemical reactions are generally performed under pressure and temperature conditions different from normal ones, they are carried out within a reaction chamber cut off from the outside air. As manufacturing steps of the semiconductor device, using such chemical reactions, may be mentioned, various ones such as etching, ashing, chemical vapor deposition (CVD), sputtering, ion implantation, evaporation, vacuum bake, SEM measurement, etc. There may be a case in which gaseous and liquid toxic substances are used in chemical reaction. The transfer of chemical reactants is carefully carried out.
A semiconductor manufacturing apparatus for manufacturing the semiconductor device under the above-described presumption has routes for transferring liquid and gaseous substances, which exist therein in large numbers. For instance, a CVD system will be considered by way of example. In the CVD system, several types of reaction gases which actually produce reaction by CVD, and several types of carrier gases for maintaining the environment of reaction are introduced into a reaction chamber. The carrier gases are high in stability in most cases, whereas since the reaction gases cause chemical reactions, they are low in stability and often contain toxic ones. Since the CVD reaction is made at low atmospheric pressure near a vacuum, the gases are exhausted from within the reaction chamber by a vacuum pump. Since the exhausted gases contain the toxic ones and high-reactive ones as described above, there is a need to defuse or detoxify these. Therefore, the gases exhausted from the vacuum pump are discharged through a detoxification device.
Such a CVD system makes use of tubes for the purpose of transferring gases. Upon transfer of the reaction and carrier gases, etc., tubes are used to connect between a gas source such as a cylinder and an apparatus. Since the reaction and carrier gases are not so high in flow rate, tubes each small in diameter and formed of a hard material are often used as the tubes used for transfer.
On the other hand, there is a need to provide tubes larger in diameter than the above tubes between the reaction chamber and the vacuum pump and between the vacuum pump and the detoxification device in order to ensure flow rates used for evacuation. As such tubes, may be mentioned a flexible tube. The flexible tube is made up of a thin metal sheet and has concavo-convex surfaces.
When a device and other hard ones collide with the convex portions of the surface of the flexible tube, the convex portions are deformed and destroyed, so that the degree of vacuum in the reaction chamber is not maintained, thus yielding a leak. A flexible tube of a vacuum system is often used under a large atmospheric pressure difference between atmospheric pressure under normal vacuum and the atmospheric pressure. Thus, such a flexible tube is deformed and broken according to the difference in atmospheric pressure between the inside and outside of the flexible tube. There may be a case in which when the flexible tube is accidentally brought into contact with an electric wiring, a short occurs so that a small hole is formed in the flexible tube.
Since process conditions executed within the reaction chamber become different from process conditions to be originally set where the degree of vacuum in the reaction chamber is not kept, there is a possibility that the optimum process will become unexecutable.